In wireless communication systems, transmit beamforming techniques are employed to improve the reliability and throughput of a wireless link between one device having a plurality of antennas and another device. When transmit beamforming one or more signals, multiple copies of the transmitted signal(s) are sent from multiple antennas and the signals supplied to the respective antennas are weighted (in magnitude and phase) in such a way that they will be optimally combined at the intended receiver device. The antenna weights to be applied to the copies of the transmit signal are extracted from phase and magnitude information of signals received from the other device. Therefore, in order to achieve the benefits of transmit beamforming, the receive and transmit channels need to be symmetric, and the phase and magnitude differences between the receivers and transmitters in the device doing the transmit beamforming need to compensated.
There are numerous antenna calibration techniques available, but all of them rather complex computations, intricate procedures for measurements and/or specific hardware to achieve the desired compensation.